(19)
(11) EP 0 286 070 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
12.09.1990 Bulletin 1990/37

(43) Date of publication A2:
12.10.1988 Bulletin 1988/41

(21) Application number: 88105481.1

(22) Date of filing: 06.04.1988
(51) International Patent Classification (IPC)4: G11B 13/04, G11B 11/10
(84) Designated Contracting States:
DE ES FR GB IT NL SE

(30) Priority: 10.04.1987 JP 55202/87 U

(71) Applicant: FUJITSU LIMITED
Kawasaki-shi, Kanagawa 211 (JP)

(72) Inventor:
  • Ichihara, Junichi
    Yokohama-shi Kanagawa, 227 (JP)

(74) Representative: Schmidt-Evers, Jürgen, Dipl.-Ing. et al
Patentanwälte Mitscherlich & Partner, Postfach 33 06 09
80066 München
80066 München (DE)


(56) References cited: : 
   
       


    (54) A magnetic bias coil of a magneto-optical recording apparatus


    (57) The electromagnetic coil (5) for applying a magnetic bias field (8) to the recording bit (1-1) of a magneto­optical recording disk apparatus is provided with a yoke (7) made of soft magnetic material, such as soft iron. The yoke (7) surrounds the coil's (5) outer round side (51) as well as the coil's flat side (52) opposite from the disk (1) side. The light beam (21) or the optical system is arranged in an opening of the yoke (7) on the coil's (5) flat side (52). The yoke (7) reduces the magnetic resistance of the coil (5), thus increases the magnetic field intensity at the recording bit (1-1) which requires a magnetic field intensity over a certain level. Conse­quently, the required magnetic field intensity is achieved with less coil (5) current, in other words, within a reasonable range of the coil's (5) temperature rise.







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